Population characteristics of the crab Monodaeus couchii (Crustacea, Brachyura, Xanthidae) in the Western Mediterranean

Abstract

Some aspects of the biology of the bathyal crab Monodaeus couchii from the North Tyrrhenian Sea, Sardinian Channel and Catalan Sea (Western Mediterranean) have been studied. The occurrence depth range has been found to be of between 80 and 748 m. The sex-ratio was found to be highly biassed towards males in the three study areas. The crabs are sexually dimorphic, adult males being larger than adult females. There appears to be seasonality in reproduction: ovigerous females were only collected in October, November and December. Puberty moult, as determined by morphological changes of the chelae, takes place in males within a size range of 11-16 mm carapace length. This species is heterochelic, with most males being right-handed. M. couchii is an opportunistic predator but seems to be also able of deposit feeding and scavenging.